summaryrefslogtreecommitdiffstats
path: root/irkerd
blob: d42f56e827a07c7f6f171182fb93ab3d5da750df (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
#!/usr/bin/env python
"""
irkerd - a simple IRC multiplexer daemon

Listens for JSON objects of the form {'to':<irc-url>, 'privmsg':<text>}
and relays messages to IRC channels. Each request must be followed by
a newline.

The <text> must be a string.  The value of the 'to' attribute can be a
string containing an IRC URL (e.g. 'irc://chat.freenet.net/botwar') or
a list of such strings; in the latter case the message is broadcast to
all listed channels.  Note that the channel portion of the URL need
*not* have a leading '#' unless the channel name itself does.

Design and code by Eric S. Raymond <esr@thyrsus.com>. See the project
resource page at <http://www.catb.org/~esr/irker/>.

Requires Python 2.7, or:
* 2.6 with the argparse package installed.
* Any 3.x

"""
# SPDX-License-Identifier: BSD-2-Clause

# These things might need tuning

HOST = "localhost"
PORT = 6659

PROXY_TYPE = None # Use proxy if set 1: SOCKS4, 2: SOCKS5, 3: HTTP
PROXY_HOST = ""
PROXY_PORT = 1080

XMIT_TTL = (3 * 60 * 60)	# Time to live, seconds from last transmit
PING_TTL = (15 * 60)		# Time to live, seconds from last PING
HANDSHAKE_TTL = 60		# Time to live, seconds from nick transmit
CHANNEL_TTL = (3 * 60 * 60)	# Time to live, seconds from last transmit
DISCONNECT_TTL = (24 * 60 * 60)	# Time to live, seconds from last connect
UNSEEN_TTL = 60			# Time to live, seconds since first request
CHANNEL_MAX = 18		# Max channels open per socket (default)
ANTI_FLOOD_DELAY = 1.0		# Anti-flood delay after transmissions, seconds
ANTI_BUZZ_DELAY = 0.09		# Anti-buzz delay after queue-empty check
CONNECTION_MAX = 200		# To avoid hitting a thread limit
RECONNECT_DELAY = 3		# Don't spam servers with connection attempts

# No user-serviceable parts below this line

version = "2.19"

import argparse
import logging
import logging.handlers
import json
import os
import os.path
try:  # Python 3
    import queue
except ImportError:  # Python 2
    import Queue as queue
import random
import re
import select
import signal
import socket
try:
    import socks
    socks_on = True
except ImportError:
    socks_on = False
try:  # Python 3
    import socketserver
except ImportError:  # Python 2
    import SocketServer as socketserver
import ssl
import sys
import threading
import time
import traceback
try:  # Python 3
    import urllib.parse as urllib_parse
except ImportError:  # Python 2
    import urlparse as urllib_parse


LOG = logging.getLogger(__name__)
LOG.setLevel(logging.ERROR)
LOG_LEVELS = ['critical', 'error', 'warning', 'info', 'debug']

try:  # Python 2
    UNICODE_TYPE = unicode
except NameError:  # Python 3
    UNICODE_TYPE = str


# Sketch of implementation:
#
# One Irker object manages multiple IRC sessions.  It holds a map of
# Dispatcher objects, one per (server, port) combination, which are
# responsible for routing messages to one of any number of Connection
# objects that do the actual socket conversations.  The reason for the
# Dispatcher layer is that IRC daemons limit the number of channels a
# client (that is, from the daemon's point of view, a socket) can be
# joined to, so each session to a server needs a flock of Connection
# instances each with its own socket.
#
# Connections are timed out and removed when either they haven't seen a
# PING for a while (indicating that the server may be stalled or down)
# or there has been no message traffic to them for a while, or
# even if the queue is nonempty but efforts to connect have failed for
# a long time.
#
# There are multiple threads. One accepts incoming traffic from all
# servers.  Each Connection also has a consumer thread and a
# thread-safe message queue.  The program main appends messages to
# queues as JSON requests are received; the consumer threads try to
# ship them to servers.  When a socket write stalls, it only blocks an
# individual consumer thread; if it stalls long enough, the session
# will be timed out. This solves the biggest problem with a
# single-threaded implementation, which is that you can't count on a
# single stalled write not hanging all other traffic - you're at the
# mercy of the length of the buffers in the TCP/IP layer.
#
# Message delivery is thus not reliable in the face of network stalls,
# but this was considered acceptable because IRC (notoriously) has the
# same problem - there is little point in reliable delivery to a relay
# that is down or unreliable.
#
# This code uses only NICK, JOIN, PART, MODE, PRIVMSG, USER, and QUIT.
# It is strictly compliant to RFC1459, except for the interpretation and
# use of the DEAF and CHANLIMIT and (obsolete) MAXCHANNELS features.
#
# CHANLIMIT is as described in the Internet RFC draft
# draft-brocklesby-irc-isupport-03 at <http://www.mirc.com/isupport.html>.
# The ",isnick" feature is as described in
# <http://ftp.ics.uci.edu/pub/ietf/uri/draft-mirashi-url-irc-01.txt>.

# Historical note: the IRCClient and IRCServerConnection classes
# (~270LOC) replace the overweight, overcomplicated 3KLOC mass of
# irclib code that irker formerly used as a service library.  They
# still look similar to parts of irclib because I contributed to that
# code before giving up on it.

class IRCError(BaseException):
    "An IRC exception"
    pass

class InvalidRequest(ValueError):
    "An invalid JSON request"
    pass

class IRCClient():
    "An IRC client session to one or more servers."
    def __init__(self):
        self.mutex = threading.RLock()
        self.server_connections = []
        self.event_handlers = {}
        self.add_event_handler("ping",
                               lambda c, e: c.ship("PONG %s" % e.target))

    def newserver(self):
        "Initialize a new server-connection object."
        conn = IRCServerConnection(self)
        with self.mutex:
            self.server_connections.append(conn)
        return conn

    def spin(self, timeout=0.2):
        "Spin processing data from connections forever."
        # Outer loop should specifically *not* be mutex-locked.
        # Otherwise no other thread would ever be able to change
        # the shared state of an IRC object running this function.
        while True:
            nextsleep = 0
            with self.mutex:
                connected = [x for x in self.server_connections
                             if x is not None and x.socket is not None]
                sockets = [x.socket for x in connected]
                if sockets:
                    connmap = dict([(c.socket.fileno(), c) for c in connected])
                    (insocks, _o, _e) = select.select(sockets, [], [], timeout)
                    for s in insocks:
                        try:
                            connmap[s.fileno()].consume()
                        except UnicodeDecodeError as e:
                            LOG.warn('{0}: invalid encoding ({1})'.format(
                                self, e))
                else:
                    nextsleep = timeout
            time.sleep(nextsleep)

    def add_event_handler(self, event, handler):
        "Set a handler to be called later."
        with self.mutex:
            event_handlers = self.event_handlers.setdefault(event, [])
            event_handlers.append(handler)

    def handle_event(self, connection, event):
        with self.mutex:
            h = self.event_handlers
            th = h.get("all_events", []) + h.get(event.type, [])
            for handler in th:
                handler(connection, event)

    def drop_connection(self, connection):
        with self.mutex:
            self.server_connections.remove(connection)


class LineBufferedStream():
    "Line-buffer a read stream."
    _crlf_re = re.compile(b'\r?\n')

    def __init__(self):
        self.buffer = b''

    def append(self, newbytes):
        self.buffer += newbytes

    def lines(self):
        "Iterate over lines in the buffer."
        lines = self._crlf_re.split(self.buffer)
        self.buffer = lines.pop()
        return iter(lines)

    def __iter__(self):
        return self.lines()

class IRCServerConnectionError(IRCError):
    pass

class IRCServerConnection():
    command_re = re.compile("^(:(?P<prefix>[^ ]+) +)?(?P<command>[^ ]+)( *(?P<argument> .+))?")
    # The full list of numeric-to-event mappings is in Perl's Net::IRC.
    # We only need to ensure that if some ancient server throws numerics
    # for the ones we actually want to catch, they're mapped.
    codemap = {
        "001": "welcome",
        "005": "featurelist",
        "432": "erroneusnickname",
        "433": "nicknameinuse",
        "436": "nickcollision",
        "437": "unavailresource",
    }

    def __init__(self, master):
        self.master = master
        self.socket = None

    # PROTOCOL_SSLv23 selects the highest version that both client and server support
    def _wrap_socket(self, socket, target, certfile=None, cafile=None,
                     protocol=ssl.PROTOCOL_SSLv23):
        try:  # Python 3.2 and greater
            ssl_context = ssl.SSLContext(protocol)
        except AttributeError:  # Python < 3.2
            self.socket = ssl.wrap_socket(
                socket, certfile=certfile, cert_reqs=ssl.CERT_REQUIRED,
                ssl_version=protocol, ca_certs=cafile)
        else:
            ssl_context.verify_mode = ssl.CERT_REQUIRED
            if certfile:
                ssl_context.load_cert_chain(certfile)
            if cafile:
                ssl_context.load_verify_locations(cafile=cafile)
            else:
                ssl_context.set_default_verify_paths()
            kwargs = {}
            if ssl.HAS_SNI:
                kwargs['server_hostname'] = target.servername
            self.socket = ssl_context.wrap_socket(socket, **kwargs)
        return self.socket

    def _check_hostname(self, target):
        if hasattr(ssl, 'match_hostname'):  # Python >= 3.2
            cert = self.socket.getpeercert()
            try:
                ssl.match_hostname(cert, target.servername)
            except ssl.CertificateError as e:
                raise IRCServerConnectionError(
                    'Invalid SSL/TLS certificate: %s' % e)
        else:  # Python < 3.2
            LOG.warning(
                'cannot check SSL/TLS hostname with Python %s' % sys.version)

    def connect(self, target, nickname, username=None, realname=None,
                **kwargs):
        LOG.debug("connect(server=%r, port=%r, nickname=%r, ...)" % (
            target.servername, target.port, nickname))
        if self.socket is not None:
            self.disconnect("Changing servers")

        self.buffer = LineBufferedStream()
        self.event_handlers = {}
        self.real_server_name = ""
        self.target = target
        self.nickname = nickname
        try:
            if socks_on and PROXY_TYPE:
                self.socket = socks.socksocket(socket.AF_INET,socket.SOCK_STREAM)
                self.socket.set_proxy(PROXY_TYPE, PROXY_HOST, PROXY_PORT)
            else:
                self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            if target.ssl:
                self.socket = self._wrap_socket(
                    socket=self.socket, target=target, **kwargs)
            self.socket.bind(('', 0))
            self.socket.connect((target.servername, target.port))
        except socket.error as err:
            raise IRCServerConnectionError("Couldn't connect to socket: %s" % err)

        if target.ssl:
            self._check_hostname(target=target)
        if target.password:
            self.ship("PASS " + target.password)
        self.nick(self.nickname)
        self.user(
            username=target.username or username or 'irker',
            realname=realname or 'irker relaying client')
        return self

    def close(self):
        # Without this thread lock, there is a window during which
        # select() can find a closed socket, leading to an EBADF error.
        with self.master.mutex:
            self.disconnect("Closing object")
            self.master.drop_connection(self)

    def consume(self):
        try:
            incoming = self.socket.recv(16384)
        except socket.error:
            # Server hung up on us.
            self.disconnect("Connection reset by peer")
            return
        if not incoming:
            # Dead air also indicates a connection reset.
            self.disconnect("Connection reset by peer")
            return

        self.buffer.append(incoming)

        for line in self.buffer:
            if not isinstance(line, UNICODE_TYPE):
                line = UNICODE_TYPE(line, 'utf-8')
                LOG.debug("FROM: %s" % line)

            if not line:
                continue

            prefix = None
            command = None
            arguments = None
            self.handle_event(Event("every_raw_message",
                                    self.real_server_name,
                                    None,
                                    [line]))

            m = IRCServerConnection.command_re.match(line)
            if m.group("prefix"):
                prefix = m.group("prefix")
                if not self.real_server_name:
                    self.real_server_name = prefix
            if m.group("command"):
                command = m.group("command").lower()
            if m.group("argument"):
                a = m.group("argument").split(" :", 1)
                arguments = a[0].split()
                if len(a) == 2:
                    arguments.append(a[1])

            command = IRCServerConnection.codemap.get(command, command)
            if command in ["privmsg", "notice"]:
                target = arguments.pop(0)
            else:
                target = None

                if command == "quit":
                    arguments = [arguments[0]]
                elif command == "ping":
                    target = arguments[0]
                else:
                    target = arguments[0]
                    arguments = arguments[1:]

            LOG.debug("command: %s, source: %s, target: %s, arguments: %s" % (
                command, prefix, target, arguments))
            self.handle_event(Event(command, prefix, target, arguments))

    def handle_event(self, event):
        self.master.handle_event(self, event)
        if event.type in self.event_handlers:
            for fn in self.event_handlers[event.type]:
                fn(self, event)

    def is_connected(self):
        return self.socket is not None

    def disconnect(self, message=""):
        if self.socket is None:
            return
        # Don't send a QUIT here - causes infinite loop!
        try:
            self.socket.shutdown(socket.SHUT_WR)
            self.socket.close()
        except socket.error:
            pass
        del self.socket
        self.socket = None
        self.handle_event(
            Event("disconnect", self.target.server, "", [message]))

    def join(self, channel, key=""):
        self.ship("JOIN %s%s" % (channel, (key and (" " + key))))

    def mode(self, target, command):
        self.ship("MODE %s %s" % (target, command))

    def nick(self, newnick):
        self.ship("NICK " + newnick)

    def part(self, channel, message=""):
        cmd_parts = ['PART', channel]
        if message:
            cmd_parts.append(message)
        self.ship(' '.join(cmd_parts))

    def privmsg(self, target, text):
        self.ship("PRIVMSG %s :%s" % (target, text))

    def quit(self, message=""):
        self.ship("QUIT" + (message and (" :" + message)))

    def user(self, username, realname):
        self.ship("USER %s 0 * :%s" % (username, realname))

    def ship(self, string):
        "Ship a command to the server, appending CR/LF"
        try:
            self.socket.send(string.encode('utf-8') + b'\r\n')
            LOG.debug("TO: %s" % string)
        except socket.error:
            self.disconnect("Connection reset by peer.")

class Event(object):
    def __init__(self, evtype, source, target, arguments=None):
        self.type = evtype
        self.source = source
        self.target = target
        if arguments is None:
            arguments = []
        self.arguments = arguments

def is_channel(string):
    return string and string[0] in "#&+!"

class Connection:
    def __init__(self, irker, target, nick_template, nick_needs_number=False,
                 password=None, **kwargs):
        self.irker = irker
        self.target = target
        self.nick_template = nick_template
        self.nick_needs_number = nick_needs_number
        self.password = password
        self.kwargs = kwargs
        self.nick_trial = None
        self.connection = None
        self.status = None
        self.last_xmit = time.time()
        self.last_ping = time.time()
        self.channels_joined = {}
        self.channel_limits = {}
        # The consumer thread
        self.queue = queue.Queue()
        self.thread = None
    def nickname(self, n=None):
        "Return a name for the nth server connection."
        if n is None:
            n = self.nick_trial
        if self.nick_needs_number:
            return self.nick_template % n
        else:
            return self.nick_template
    def handle_ping(self):
        "Register the fact that the server has pinged this connection."
        self.last_ping = time.time()
    def handle_welcome(self):
        "The server says we're OK, with a non-conflicting nick."
        self.status = "ready"
        LOG.info("nick %s accepted" % self.nickname())
        if self.password:
            self.connection.privmsg("nickserv", "identify %s" % self.password)
    def handle_badnick(self):
        "The server says our nick is ill-formed or has a conflict."
        LOG.info("nick %s rejected" % self.nickname())
        if self.nick_needs_number:
            # Randomness prevents a malicious user or bot from
            # anticipating the next trial name in order to block us
            # from completing the handshake.
            self.nick_trial += random.randint(1, 3)
            self.last_xmit = time.time()
            self.connection.nick(self.nickname())
        # Otherwise fall through, it might be possible to
        # recover manually.
    def handle_disconnect(self):
        "Server disconnected us for flooding or some other reason."
        self.connection = None
        if self.status != "expired":
            self.status = "disconnected"
        # Avoid flooding the server if it disconnects
        # immediately on sucessful login.
        time.sleep(RECONNECT_DELAY)
    def handle_kick(self, outof):
        "We've been kicked."
        self.status = "handshaking"
        try:
            del self.channels_joined[outof]
        except KeyError:
            LOG.error("irkerd: kicked by %s from %s that's not joined" % (
                self.target, outof))
        qcopy = []
        while not self.queue.empty():
            (channel, message, key) = self.queue.get()
            if channel != outof:
                qcopy.append((channel, message, key))
        for (channel, message, key) in qcopy:
            self.queue.put((channel, message, key))
        self.status = "ready"
    def enqueue(self, channel, message, key, quit_after=False):
        "Enque a message for transmission."
        if self.thread is None or not self.thread.is_alive():
            self.status = "unseen"
            self.thread = threading.Thread(target=self.dequeue)
            self.thread.setDaemon(True)
            self.thread.start()
        self.queue.put((channel, message, key))
        if quit_after:
            self.queue.put((channel, None, key))
    def dequeue(self):
        "Try to ship pending messages from the queue."
        try:
            while True:
                # We want to be kind to the IRC servers and not hold unused
                # sockets open forever, so they have a time-to-live.  The
                # loop is coded this particular way so that we can drop
                # the actual server connection when its time-to-live
                # expires, then reconnect and resume transmission if the
                # queue fills up again.
                if self.queue.empty():
                    # Queue is empty, at some point we want to time out
                    # the connection rather than holding a socket open in
                    # the server forever.
                    now = time.time()
                    xmit_timeout = now > self.last_xmit + XMIT_TTL
                    ping_timeout = now > self.last_ping + PING_TTL
                    if self.status == "disconnected":
                        # If the queue is empty, we can drop this connection.
                        self.status = "expired"
                        break
                    elif xmit_timeout or ping_timeout:
                        LOG.info((
                            "timing out connection to %s at %s "
                            "(ping_timeout=%s, xmit_timeout=%s)") % (
                            self.target, time.asctime(), ping_timeout,
                            xmit_timeout))
                        with self.irker.irc.mutex:
                            self.connection.context = None
                            self.connection.quit("transmission timeout")
                            self.connection = None
                        self.status = "disconnected"
                    else:
                        # Prevent this thread from hogging the CPU by pausing
                        # for just a little bit after the queue-empty check.
                        # As long as this is less that the duration of a human
                        # reflex arc it is highly unlikely any human will ever
                        # notice.
                        time.sleep(ANTI_BUZZ_DELAY)
                elif self.status == "disconnected" \
                         and time.time() > self.last_xmit + DISCONNECT_TTL:
                    # Queue is nonempty, but the IRC server might be
                    # down. Letting failed connections retain queue
                    # space forever would be a memory leak.
                    self.status = "expired"
                    break
                elif not self.connection and self.status != "expired":
                    # Queue is nonempty but server isn't connected.
                    with self.irker.irc.mutex:
                        self.connection = self.irker.irc.newserver()
                        self.connection.context = self
                        # Try to avoid colliding with other instances
                        self.nick_trial = random.randint(1, 990)
                        self.channels_joined = {}
                        try:
                            # This will throw
                            # IRCServerConnectionError on failure
                            self.connection.connect(
                                target=self.target,
                                nickname=self.nickname(),
                                **self.kwargs)
                            self.status = "handshaking"
                            LOG.info("XMIT_TTL bump (%s connection) at %s" % (
                                self.target, time.asctime()))
                            self.last_xmit = time.time()
                            self.last_ping = time.time()
                        except IRCServerConnectionError as e:
                            LOG.error("irkerd: %s" % e)
                            self.status = "expired"
                            break
                elif self.status == "handshaking":
                    if time.time() > self.last_xmit + HANDSHAKE_TTL:
                        self.status = "expired"
                        break
                    else:
                        # Don't buzz on the empty-queue test while we're
                        # handshaking
                        time.sleep(ANTI_BUZZ_DELAY)
                elif self.status == "unseen" \
                         and time.time() > self.last_xmit + UNSEEN_TTL:
                    # Nasty people could attempt a denial-of-service
                    # attack by flooding us with requests with invalid
                    # servernames. We guard against this by rapidly
                    # expiring connections that have a nonempty queue but
                    # have never had a successful open.
                    self.status = "expired"
                    break
                elif self.status == "ready":
                    (channel, message, key) = self.queue.get()
                    if channel not in self.channels_joined:
                        self.connection.join(channel, key=key)
                        LOG.info("joining %s on %s." % (channel, self.target))
                    # None is magic - it's a request to quit the server
                    if message is None:
                        self.connection.quit()
                    # An empty message might be used as a keepalive or
                    # to join a channel for logging, so suppress the
                    # privmsg send unless there is actual traffic.
                    elif message:
                        for segment in message.split("\n"):
                            # Truncate the message if it's too long,
                            # but we're working with characters here,
                            # not bytes, so we could be off.
                            # 500 = 512 - CRLF - 'PRIVMSG ' - ' :'
                            maxlength = 500 - len(channel)
                            if len(segment) > maxlength:
                                segment = segment[:maxlength]
                            try:
                                self.connection.privmsg(channel, segment)
                            except ValueError as err:
                                LOG.warning((
                                    "rejected a message to %s on %s "
                                    "because: %s") % (
                                    channel, self.target, UNICODE_TYPE(err)))
                                LOG.debug(traceback.format_exc())
                            time.sleep(ANTI_FLOOD_DELAY)
                    self.last_xmit = self.channels_joined[channel] = time.time()
                    LOG.info("XMIT_TTL bump (%s transmission) at %s" % (
                        self.target, time.asctime()))
                    self.queue.task_done()
                elif self.status == "expired":
                    LOG.error(
                        "irkerd: we're expired but still running! This is a bug.")
                    break
        except Exception as e:
            LOG.error("irkerd: exception %s in thread for %s" % (e, self.target))
            # Maybe this should have its own status?
            self.status = "expired"
            LOG.debug(traceback.format_exc())
        finally:
            # Make sure we don't leave any zombies behind
            if self.connection:
                self.connection.close()
    def live(self):
        "Should this connection not be scavenged?"
        return self.status != "expired"
    def joined_to(self, channel):
        "Is this connection joined to the specified channel?"
        return channel in self.channels_joined
    def accepting(self, channel):
        "Can this connection accept a join of this channel?"
        if self.channel_limits:
            match_count = 0
            for already in self.channels_joined:
                # This obscure code is because the RFCs allow separate limits
                # by channel type (indicated by the first character of the name)
                # a feature that is almost never actually used.
                if already[0] == channel[0]:
                    match_count += 1
            return match_count < self.channel_limits.get(channel[0], CHANNEL_MAX)
        else:
            return len(self.channels_joined) < CHANNEL_MAX

class Target():
    "Represent a transmission target."
    def __init__(self, url):
        self.url = url
        parsed = urllib_parse.urlparse(url)
        self.ssl = parsed.scheme == 'ircs'
        if self.ssl:
            default_ircport = 6697
        else:
            default_ircport = 6667
        self.username = parsed.username
        self.password = parsed.password
        self.servername = parsed.hostname
        self.port = parsed.port or default_ircport
        # IRC channel names are case-insensitive.  If we don't smash
        # case here we may run into problems later. There was a bug
        # observed on irc.rizon.net where an irkerd user specified #Channel,
        # got kicked, and irkerd crashed because the server returned
        # "#channel" in the notification that our kick handler saw.
        self.channel = parsed.path.lstrip('/').lower()
        # This deals with a tweak in recent versions of urlparse.
        if parsed.fragment:
            self.channel += "#" + parsed.fragment
        isnick = self.channel.endswith(",isnick")
        if isnick:
            self.channel = self.channel[:-7]
        if self.channel and not isnick and self.channel[0] not in "#&+":
            self.channel = "#" + self.channel
        # support both channel?secret and channel?key=secret
        self.key = ""
        if parsed.query:
            self.key = re.sub("^key=", "", parsed.query)

    def __str__(self):
        "Represent this instance as a string"
        return self.servername or self.url or repr(self)

    def validate(self):
        "Raise InvalidRequest if the URL is missing a critical component"
        if not self.servername:
            raise InvalidRequest(
                'target URL missing a servername: %r' % self.url)
        if not self.channel:
            raise InvalidRequest(
                'target URL missing a channel: %r' % self.url)
    def server(self):
        "Return a hashable tuple representing the destination server."
        return (self.servername, self.port)

class Dispatcher:
    "Manage connections to a particular server-port combination."
    def __init__(self, irker, **kwargs):
        self.irker = irker
        self.kwargs = kwargs
        self.connections = []
    def dispatch(self, channel, message, key, quit_after=False):
        "Dispatch messages for our server-port combination."
        # First, check if there is room for another channel
        # on any of our existing connections.
        connections = [x for x in self.connections if x.live()]
        eligibles = [x for x in connections if x.joined_to(channel)] \
                    or [x for x in connections if x.accepting(channel)]
        if eligibles:
            eligibles[0].enqueue(channel, message, key, quit_after)
            return
        # All connections are full up. Look for one old enough to be
        # scavenged.
        ancients = []
        for connection in connections:
            for (chan, age) in connections.channels_joined.items():
                if age < time.time() - CHANNEL_TTL:
                    ancients.append((connection, chan, age))
        if ancients:
            ancients.sort(key=lambda x: x[2])
            (found_connection, drop_channel, _drop_age) = ancients[0]
            found_connection.part(drop_channel, "scavenged by irkerd")
            del found_connection.channels_joined[drop_channel]
            #time.sleep(ANTI_FLOOD_DELAY)
            found_connection.enqueue(channel, message, key, quit_after)
            return
        # All existing channels had recent activity
        newconn = Connection(self.irker, **self.kwargs)
        self.connections.append(newconn)
        newconn.enqueue(channel, message, key, quit_after)
    def live(self):
        "Does this server-port combination have any live connections?"
        self.connections = [x for x in self.connections if x.live()]
        return len(self.connections) > 0
    def pending(self):
        "Return all connections with pending traffic."
        return [x for x in self.connections if not x.queue.empty()]
    def last_xmit(self):
        "Return the time of the most recent transmission."
        return max(x.last_xmit for x in self.connections)

class Irker:
    "Persistent IRC multiplexer."
    def __init__(self, logfile=None, **kwargs):
        self.logfile = logfile
        self.kwargs = kwargs
        self.irc = IRCClient()
        self.irc.add_event_handler("ping", self._handle_ping)
        self.irc.add_event_handler("welcome", self._handle_welcome)
        self.irc.add_event_handler("erroneusnickname", self._handle_badnick)
        self.irc.add_event_handler("nicknameinuse", self._handle_badnick)
        self.irc.add_event_handler("nickcollision", self._handle_badnick)
        self.irc.add_event_handler("unavailresource", self._handle_badnick)
        self.irc.add_event_handler("featurelist", self._handle_features)
        self.irc.add_event_handler("disconnect", self._handle_disconnect)
        self.irc.add_event_handler("kick", self._handle_kick)
        self.irc.add_event_handler("every_raw_message", self._handle_every_raw_message)
        self.servers = {}
    def thread_launch(self):
        thread = threading.Thread(target=self.irc.spin)
        thread.setDaemon(True)
        self.irc._thread = thread
        thread.start()
    def _handle_ping(self, connection, _event):
        "PING arrived, bump the last-received time for the connection."
        if connection.context:
            connection.context.handle_ping()
    def _handle_welcome(self, connection, _event):
        "Welcome arrived, nick accepted for this connection."
        if connection.context:
            connection.context.handle_welcome()
    def _handle_badnick(self, connection, _event):
        "Nick not accepted for this connection."
        if connection.context:
            connection.context.handle_badnick()
    def _handle_features(self, connection, event):
        "Determine if and how we can set deaf mode."
        if connection.context:
            cxt = connection.context
            arguments = event.arguments
            for lump in arguments:
                if lump.startswith("DEAF="):
                    if not self.logfile:
                        connection.mode(cxt.nickname(), "+"+lump[5:])
                elif lump.startswith("MAXCHANNELS="):
                    m = int(lump[12:])
                    for pref in "#&+":
                        cxt.channel_limits[pref] = m
                    LOG.info("%s maxchannels is %d" % (connection.target, m))
                elif lump.startswith("CHANLIMIT=#:"):
                    limits = lump[10:].split(",")
                    try:
                        for token in limits:
                            (prefixes, limit) = token.split(":")
                            limit = int(limit)
                            for c in prefixes:
                                cxt.channel_limits[c] = limit
                        LOG.info("%s channel limit map is %s" % (
                            connection.target, cxt.channel_limits))
                    except ValueError:
                        LOG.error("irkerd: ill-formed CHANLIMIT property")
    def _handle_disconnect(self, connection, _event):
        "Server hung up the connection."
        LOG.info("server %s disconnected" % connection.target)
        connection.close()
        if connection.context:
            connection.context.handle_disconnect()
    def _handle_kick(self, connection, event):
        "Server hung up the connection."
        target = event.target
        LOG.info("irker has been kicked from %s on %s" % (
            target, connection.target))
        if connection.context:
            connection.context.handle_kick(target)
    def _handle_every_raw_message(self, _connection, event):
        "Log all messages when in watcher mode."
        if self.logfile:
            with open(self.logfile, "ab") as logfp:
                message = u"%03f|%s|%s\n" % \
                          (time.time(), event.source, event.arguments[0])
                logfp.write(message.encode('utf-8'))

    def pending(self):
        "Do we have any pending message traffic?"
        return [k for (k, v) in self.servers.items() if v.pending()]

    def _parse_request(self, line):
        "Request-parsing helper for the handle() method"
        request = json.loads(line.strip())
        if not isinstance(request, dict):
            raise InvalidRequest(
                "request is not a JSON dictionary: %r" % request)
        if "to" not in request or "privmsg" not in request:
            raise InvalidRequest(
                "malformed request - 'to' or 'privmsg' missing: %r" % request)
        channels = request['to']
        message = request['privmsg']
        if not isinstance(channels, (list, UNICODE_TYPE)):
            raise InvalidRequest(
                "malformed request - unexpected channel type: %r" % channels)
        if not isinstance(message, UNICODE_TYPE):
            raise InvalidRequest(
                "malformed request - unexpected message type: %r" % message)
        if not isinstance(channels, list):
            channels = [channels]
        targets = []
        for url in channels:
            try:
                if not isinstance(url, UNICODE_TYPE):
                    raise InvalidRequest(
                        "malformed request - URL has unexpected type: %r" %
                        url)
                target = Target(url)
                target.validate()
            except InvalidRequest as e:
                LOG.error("irkerd: " + UNICODE_TYPE(e))
            else:
                targets.append(target)
        return (targets, message)

    def handle(self, line, quit_after=False):
        "Perform a JSON relay request."
        try:
            targets, message = self._parse_request(line=line)
            for target in targets:
                if target.server() not in self.servers:
                    self.servers[target.server()] = Dispatcher(
                        self, target=target, **self.kwargs)
                self.servers[target.server()].dispatch(
                    target.channel, message, target.key, quit_after=quit_after)
                # GC dispatchers with no active connections
                servernames = self.servers.keys()
                for servername in servernames:
                    if not self.servers[servername].live():
                        del self.servers[servername]
                    # If we might be pushing a resource limit even
                    # after garbage collection, remove a session.  The
                    # goal here is to head off DoS attacks that aim at
                    # exhausting thread space or file descriptors.
                    # The cost is that attempts to DoS this service
                    # will cause lots of join/leave spam as we
                    # scavenge old channels after connecting to new
                    # ones. The particular method used for selecting a
                    # session to be terminated doesn't matter much; we
                    # choose the one longest idle on the assumption
                    # that message activity is likely to be clumpy.
                    if len(self.servers) >= CONNECTION_MAX:
                        oldest = min(
                            self.servers.keys(),
                            key=lambda name: self.servers[name].last_xmit())
                        del self.servers[oldest]
        except InvalidRequest as e:
            LOG.error("irkerd: " + UNICODE_TYPE(e))
        except ValueError:
            LOG.error("irkerd: " + "can't recognize JSON on input: %r" % line)
        except RuntimeError:
            LOG.error("irkerd: " + "wildly malformed JSON blew the parser stack.")

class IrkerTCPHandler(socketserver.StreamRequestHandler):
    def handle(self):
        while True:
            line = self.rfile.readline()
            if not line:
                break
            if not isinstance(line, UNICODE_TYPE):
                line = UNICODE_TYPE(line, 'utf-8')
            irker.handle(line=line.strip())

class IrkerUDPHandler(socketserver.BaseRequestHandler):
    def handle(self):
        line = self.request[0].strip()
        #socket = self.request[1]
        if not isinstance(line, UNICODE_TYPE):
            line = UNICODE_TYPE(line, 'utf-8')
        irker.handle(line=line.strip())

def in_background():
    "Is this process running in background?"
    try:
        return os.getpgrp() != os.tcgetpgrp(1)
    except OSError:
        return True

if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description=__doc__.strip().splitlines()[0])
    parser.add_argument(
        '-c', '--ca-file', metavar='PATH',
        help='file of trusted certificates for SSL/TLS')
    parser.add_argument(
        '-e', '--cert-file', metavar='PATH',
        help='pem file used to authenticate to the server')
    parser.add_argument(
        '-d', '--log-level', metavar='LEVEL', choices=LOG_LEVELS,
        help='how much to log to the log file (one of %(choices)s)')
    parser.add_argument(
        '-H', '--host', metavar='ADDRESS', default=HOST,
        help='IP address to listen on')
    parser.add_argument(
        '-l', '--log-file', metavar='PATH',
        help='file for saving captured message traffic')
    parser.add_argument(
        '-n', '--nick', metavar='NAME', default='irker%03d',
        help="nickname (optionally with a '%%.*d' server connection marker)")
    parser.add_argument(
        '-p', '--password', metavar='PASSWORD',
        help='NickServ password')
    parser.add_argument(
        '-i', '--immediate', metavar='IRC-URL',
        help=(
            'send a single message to IRC-URL and exit.  The message is the '
            'first positional argument.'))
    parser.add_argument(
        '-V', '--version', action='version',
        version='%(prog)s {0}'.format(version))
    parser.add_argument(
        'message', metavar='MESSAGE', nargs='?',
        help='message for --immediate mode')
    args = parser.parse_args()

    if not args.log_file and in_background():
        # There's a case for falling back to address = ('localhost', 514)
        # But some systems (including OS X) disable this for security reasons.
        handler = logging.handlers.SysLogHandler(facility='daemon')
    else:
        handler = logging.StreamHandler()

    LOG.addHandler(handler)
    if args.log_level:
        log_level = getattr(logging, args.log_level.upper())
        LOG.setLevel(log_level)

    irker = Irker(
        logfile=args.log_file,
        nick_template=args.nick,
        nick_needs_number=re.search('%.*d', args.nick),
        password=args.password,
        cafile=args.ca_file,
        certfile=args.cert_file,
        )
    LOG.info("irkerd version %s" % version)
    if args.immediate:
        if not args.message:
            # We want newline to become '\n' and tab to become '\t';
            # the JSON decoder will undo these transformations.
            # This will also encode backslash, backspace, formfeed,
            # and high-half characters, which might produce unexpected
            # results on output.
            args.message = sys.stdin.read().encode("string_escape")
        irker.irc.add_event_handler("quit", lambda _c, _e: sys.exit(0))
        irker.handle('{"to":"%s","privmsg":"%s"}' % (
            args.immediate, args.message), quit_after=True)
        irker.irc.spin()
    else:
        if args.message:
            LOG.error(
                'irkerd: message argument given (%r), but --immediate not set' % (
                args.message))
            raise SystemExit(1)
        irker.thread_launch()
        try:
            tcpserver = socketserver.TCPServer((args.host, PORT), IrkerTCPHandler)
            udpserver = socketserver.UDPServer((args.host, PORT), IrkerUDPHandler)
            for server in [tcpserver, udpserver]:
                server = threading.Thread(target=server.serve_forever)
                server.setDaemon(True)
                server.start()
            try:
                signal.pause()
            except KeyboardInterrupt:
                raise SystemExit(1)
        except socket.error as e:
            LOG.error("irkerd: server launch failed: %r\n" % e)

# end